This invention relates to the art of motion converting mechanisms, and more particuarly to mechanisms for converting axial movement into rotational movement. Specifically, the present invention relates to a rotator mechanism for use in rotating a valve of an internal combustion engine and will be particularly described with reference thereto.
Rotators for rotating valves of an internal combustion engine are known. Such valve rotators include first and second parts which are mounted for movement relative to one another axially and rotatably along and about the longitudinal axis of the valve. One of the parts has pockets in which a circumferentially shiftable means is positioned for imparting relative rotation to the parts in response to relative axial movement of the parts. The shiftable means may be balls or coils of a garter spring. In the case of a garter spring, the garter spring is located in an arcuate groove in one of the parts, as is known, and on relative axial movement of the parts, the coils of the garter spring shift to effect relative rotation of the parts. U.S. Pat. No. 3,421,734 is a typical disclosure of such rotators and is incorporated herein by reference. In rotators utilizing balls, the balls move along an inclined ramp which forms the bottom of a pocket in one of the parts. Numerous patents and other publications disclose rotators utilizing balls and typical of such are U.S. Pat. No. 3,710,768 and No. 3,890,943.
In the rotators as noted above, a Belleville spring washer is interposed between the parts and comprises the primary load-carrying member therebetween. Specifically, an inner peripheral surface of the spring washer engages one of the parts, and an outer peripheral surface of the spring washer engages the other of the parts. The central portion of the spring washer engages the outer circumference of the shiftable means typically with a line contact. Upon relative axial movement of the parts, the spring washer is loaded and bows around the periphery of the shiftable means and causes a shifting of the coils of the garter spring, or shifting of the balls, as the case may be. When the parts move axially apart, the spring washer's force on the shiftable means is relieved and the shiftable means returns to its initial position. The action of the spring washer and the shiftable means results in a rotation of one of the parts relative to the other, as is well known.
In accordance with the present invention, an improved rotator mechanism of the above-noted type is provided. Specifically, the improvement centers around the fact that the spring washer and the mating shiftable means are structured to have an area contact, as opposed to the afore-mentioned line contact. The area contact between the spring washer and the mating shiftable element lowers the contact stress and wear on the mating components.
Further, and more specifically in accordance with the present invention, the advantage of lowering the contact stresses through the use of area contact between the shiftable elements and the spring washer is achieved without the necessity of affecting the means flattening load of the spring washer. Thus, the load deflection characteristics of the spring washer are not altered. The above advantages are achieved in the present invention by providing a spring washer with a circumferentially extending concave surface to receive and engage a convex surface portion of the outer periphery of the shiftable element, whether it be a qarter spring or ball, and where the thickness of the spring washer does not substantially vary throughout its extent.